The Energy/Comfort Nexus: making buildings work for people and the planet

Transcription

1 MIT Energy Initiatives Series The Energy/Comfort Nexus: making buildings work for people and the planet Gail Brager Center for the Built Environment University of California, Berkeley Clif Bar Headquarters, Emeryville, CA. Zero Net Energy retrofit & winner of Living Building Award

2 Why energy? Cartoon by Joel Pett, USA Today, Dec 2009

3 Why comfort? Source:

4 Why buildings?

5 Trends - U.S. CO2 Emissions by Sector Buildings are responsible for nearly ½ of CO2 emissions in the U.S. Source: Energy Information Administration Statistics

6 Energy use in buildings a significant % goes to thermal conditioning 42.4% 38.0 % US DOE Quadrennial Technology Review,

7 But doesn t it cost a lot to reduce energy & greenhouse gases?

8 40% of avoided emissions would result in negative cost (savings)! Costs of Reducing Global Warming

9 Improved lighting and building envelopes!

10 The Architecture 2030 Challenge All new buildings, developments, and major renovations shall be carbon-neutral by Tiered % reduction below average for that bldg type

11 Meeting the Architecture 2030 Challenge

12 Zero Net Energy Buildings (ZNE) Over a year. The building generates at least as much as it uses

13 Zero Net Energy Buildings (ZNE) Over a year. The building generates at least as much as it uses The Name Game Net zero energy Net zero site energy Net zero source energy Net zero energy emissions Net zero energy costs Zero net ready Ultra-low energy (*) Zero net energy Verified Emerging * similar to ZNE in energy use reduction, but haven t invested in on-site renewables

14 Zero Net Energy Buildings (ZNE) Definitions Net zero site energy building Net zero source energy building Net zero energy cost Net zero emission Descriptions Building produces as much energy as it consumes when measured on site Building produces the same amount of energy as the amount of source (primary) energy it consumes. Cost of the energy added to the grid by the building is same as the cost of the energy consumed by it. Net emission due to building energy consumption is zero. P. Torcellini et al., Zero energy buildings: a critical look at the definition,

15 Zero Net Energy Buildings - Setting priorities Shading Daylighting Climateresponse architecture Mechanical systems Electrical systems Use renewables after you ve done everything else! Source: Two Degrees, Chap 6, McGregor, Roberts & Cousins

16 Zero Net Energy Buildings Setting priorities Shading Daylighting Climateresponse architecture Mechanical systems Electrical systems Use renewables after you ve done everything else! Source: Two Degrees, Chap 6, McGregor, Roberts & Cousins Leaky bucket analogy

17 Trends in Zero Net Energy Buildings New Buildings Institute reports

18 Trends in ZNE (& ultra-low energy) EUI? ZNE are usually 20 EUI or less!! New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

19 Trends in ZNE (& ultra-low energy) how many? # ZNE: 60 à 160 à 332 more than doubled during last 2-year periods New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

20 Trends in ZNE (& ultra-low energy) how many? New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

21 Trends in ZNE where? Nearly all climate zones New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

22 Trends in ZNE (& ultra-low energy) where? Massachusetts in top 5 states of ZNE New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

23 Trends in ZNE (& ultra-low energy) how big? New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

24 Trends in ZNE growth by size New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

25 Trends in ZNE (& ultra-low energy) who owns? 2/3 are public buildings New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

26 Trends in ZNE (& ultra-low energy) what types? New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

27 Trends in ZNE (& ultra-low energy) who owns? 2/3 are public buildings New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

28 Trends in ZNE (& ultra-low energy) - new vs. existing 1/4 are renovations New Buildings Institute, Getting to zero status update, 2016, newbuildings.org

29 Trends in ZNE (& ultra-low energy) HVAC type? ASRHAE High Performance Magazine, Fall 2016

30 Passive Solutions 1 st then Trends in ZNE (& ultra-low energy) HVAC type? HVAC Ground Source Heat Pumps Radiant Heating/Cooling & Chilled Beams Energy Recovery Systems air and water Ventilation Natural Dedicated Outdoor Air Systems (DOAS) Demand Control Ventilation (DCV) CEILING FANS CHILLED BEAMS SPACE CONDITIONING Forced Air Radiant New Buildings Institute 2016 New Buildings Institute 2016

31 The Energy/Comfort Nexus Illustration by Viktor Koen Illustration by David Lehrer

32 Energy vs. comfort is a false dichotomy We are overcooling buildings in summer, wasting energy and making people uncomfortable.

33 Comfort zones (ASHRAE Standard 55) In practice: 71 75ºF

34 Saving (significant!) energy with a wider dead band Wider dead band reduces HVAC energy 7-15% per ºC How can we make people comfortable at the same time? Energy savings with wider dead band, CA, FL, MN conventional Hoyt, T., E. Arens, H. Zhang, 2105, Extending air temperature setpoints. Building and Environment personal comfort systems Temperature ( F) adaptive

35 Energy vs. Rent vs. People costs are 1:10:100 Source: Terrapin Bright Green 2012

36 Indoor Environmental Quality (IEQ) Thermal comfort Lighting / visual comfort Indoor air quality Acoustics

37 Are people comfortable in existing buildings?

38 CBE web-based occupant satisfaction surveys Standardized method for studying building performance from occupants point of view Rich database for evaluation of new technologies buildings 100,000+ responses Uses Commissioning Diagnostics Benchmarking Research

39 CBE occupant satisfaction survey, office buildings > 50% are dissatisfied with temperature When Median < 0, > 50% are dissatisfied N = 53,000 occupants, 351 buildings Frontczak M, Schiavon S, et al Indoor Air Journal

40 Paradigm shifts in the energy/comfort nexus Artificial/active à Natural/passive/hybrid Centralized à Personal control Air à Water (radiant) Thermal neutrality à Thermal delight Packard Foundation. Source: EHDD

41 meh Artificial / Active yay! Natural / Passive (& Hybrid)

42 Adaptive comfort standard for naturally ventilated buildings

43 Adaptive comfort standard for naturally ventilated buildings 21,000 observations (indoor climate & surveys) buildings - 4 continents - broad range of climate zones. Separate analysis for : - centrally-controlled air-conditioned (HVAC) - naturally ventilated (NV) Statistical models produced an adaptive comfort standard for ASHRAE Std. 55!!!!!!!!!!!!!!!!!!!!!

44 Conventional vs. adaptive approaches Conventional standards Based on laboratory studies (Laboratory ¹ Real buildings) One-size-fits all: Universally applied to all climates, cultures, and building types Adaptive comfort theory Based on field data 3 types of adaptation: - physiological - behavioral - psychological Satisfaction influenced by expectations & context

45 Selected results: field studies Centrally-controlled HVAC bldgs Naturally ventilated bldgs Lines are weighted linear regresssions through the data points (not shown) Predicted: Lab-based heat-balance model Observed: Field-based adaptive model dedear and Brager

46 Adaptive Comfort Standard in ASHRAE Std. 55 Replaced optimum temperature with a range indoor operative temperature ( o C) F 59 F 68 F 77 F 86 F 95 F 90% acceptability limits 80% acceptability limits mean monthly outdoor air temperature ( o C) Replaced ET* as climate index Also replaced monthly with running mean 86.0 F 82.4 F 78.8 F 75.2 F 71.6 F 68.0 F 64.4 F 60.8 F

47 Mixed-mode buildings a hybrid approach Operable windows + mechanical cooling Different configurations Concurrent same space same time Change-over same space different times Zoned different spaces same time

48 Comfort and energy performance with NV and MM Adaptive comfort model development Simulation and field study studies identified appropriate comfort model for NV buildings Occupant satisfaction in mixed-mode (MM) buildings Improved thermal, air quality and overall satisfaction using occupant survey results Window control signaling systems Insights on design, occupants responses and behaviors from 16 buildings Feasibility of MM buildings in California Comfort exceedance using low-energy cooling strategies (radiant + MM) High-performance facade case studies Documenting performance, comfort and lessons learned Comfort tool development CBE developed SolarCal calculator adopted by ASHRAE

49 MM Climate Feasibility Assess climatic feasibility using metrics of comfort and energy across CA s 16 climate zones 3 basic systems: High energy baseline: Conventional forced air VAV system with chiller Low energy baseline: Natural ventilation with night flush Mixed-mode system: Radiant cooling with natural ventilation 1-9 Coastal Central Eastern

50 Simulation: case study building Case study building Kirsch Center at DeAnza College Van der Ryn Architect Simplified model 6 zones, 39 windows Designed for parametric studies Air tight, low gains, well shaded Air flow network Pressure coefficients calculated with Cp Generator Radiant floors Cooling tower charges slab overnight (free running during the day) Autosized VAV system

51 NV, MM & VAV: comparing performance Hypothetical comparison (to explain graph) (% occupant-hrs) (kbtu/sq.ft-yr) Natural Ventilation Only: Night Vent with day vent for Tout < 25C Mixed-Mode, Radiant Slab w/ NV: Same as above with night cooling of slab via cooling tower Sealed VAV: Reference case;; standard VAV with DX units

52 Mixed-mode: nutshell of our results North Coast Bay Area Central Coast Southern Coast Central Valley South East NV Only: Night Vent with day vent for Tout < 25C MM: Rad Slab w/ NV: Same as above with night cooling of slab via cooling tower Sealed VAV: Reference case;; standard VAV with DX units

53 Natural ventilation vs. Mixed mode % occupied hours above warm adaptive comfort limit (green is good)

54 meh Centralized control yay! Personal control

55 Personal comfort systems (PCS) Task/ambient approach has been widely adopted for lighting Paradigm shift: From space-based to person-based conditioning From using static indoor environmental parameters to dynamic, variable and occupantselected modes Multi-year research using simulations, laboratory, and field studies Development and testing of numerous devices Traditional mixing overhead system

56 1 st generation PCS: desktop fan & footwamer Provides control and monitoring of: User settings for fan and foot warmer Ambient air temperature Occupancy Connection to internet via USB to computer to collect and send research data 4W average 30W Fan and control unit Optional user interface Foot warmer occupancy sensing pressure plate

57 2nd generation PCS: heated & cooled chair Low power use, max: 14 W for heating 3.6W for cooling User controls for cooling and heating Saves energy by allowing wider HVAC temperature setpoints Rechargeable battery WiFi and Bluetooth communication with BMS Collects temp, humidity, occupancy & usage data 50 built for research Resistance heating strips Convectively cooled plenums Controller, Touchscreen, Bluetooth & wireless Battery - 1 week typical use Touchscreen Phone app Pasut,W., H. Zhang, E. Arens, Y. Zhai 2014, Energy efficient comfort with a heated/cooled chair, Proceedings of the 13 th International Conference Indoor Air 2014, July 7 11.

58 Demonstrated energy savings and comfort Field testing prototypes in multiple sites o Summer/winter o NV, VAV, radiant o With and without PCS (chairs, fans, food warmers, legwarmers) Comfort: At 64-84ºF more than 90% of subjects were comfortable with the chair and a desk fan Energy: Field tests have demonstrated energy savings of 60% with improved comfort

59 How can technology improve our personal control and experience? Occupant-in-the-loop controls Comfy founded by former UC Berkeley students (EECS, Architecture, CBE) Occupants make comfort requests, with social functions for shared environments Integrates with HVAC controls Based on principles from smap building information framework Comfy on a mobile device

60 Occupant-in-the-loop controls Occupants HVAC Heated/cooled PCS chairs smap * Zone control Occupant control of HVAC Selectively distribute chairs Critical zones Conflicting comfort needs Single zone, multiple rooms AHU control (*) Simple Measurement and Actuation Profile (smap) software, developed at UC Berkeley EECS Dept, connects to bldg s BACneet and allows rapid access and visualization of data from different sources

61 meh yay! Air Radiant

62 Heat capacity of air vs. water Heat Capacity of this much air = Heat Capacity of this much water Source: Peter Rumsey

63 Air vs radiant: decoupling of thermal & ventilation Image credit: Caroline Karmann

64 Air systems vs. Radiant systems Air systems Ventilation + space conditioning Design to meet a single peak cooling load value Remove heat using convection Radiant systems Decoupled ventilation and space conditioning Allow pre-conditioning the radiant layer Remove heat using convection + radiation à Traditional cooling load calculations don t account for complexities of radiant systems

65 Radiant system types (high/low mass) Thermally Activated Building System (TABS) Embedded Surface System (ESS) Radiant Panels (RP) Images source: Caroline Karmann

66 Cooling load differences: Laboratory tests Concrete pavers in floor as the non-active mass Constant heat gain applied in both settings, using thin electric resistance heating mat, loose mesh design to ceiling panels interact directly with with pavers below Constant operative temperature maintained to represent equivalent comfort (and it is prescribed as the control temperature for radiant systems) For each, 12-hour tests: Heater on for 6 hours Heater off for 6 hours Feng Bauman Schiavon 2014 Experimental comparison Energy and Buildings

67 Cooling load differences: Laboratory results Radiant system has a higher cooling rate than the air system, up to 18% higher during peak cooling load Lower floor temperatures in radiant system shows that more heat was removed compared to air system Temperature of concrete Instantaneous cooling rate pavers in floor Feng Bauman Schiavon 2014 Experimental comparison Energy and Buildings

68 New/ongoing tests at LBNL s FlexLab SIDE-BY-SIDE COMPARISON OF COOLING RATES FOR RADIANT AND FORCED AIR SYSTEMS

69 Infrared comparison 40 C RADIANT COOLING (CEILING) OPERATIVE TEMP = 26 C FORCED AIR COOLING OPERATIVE TEMP = 26 C J. WOOLLEY

70 meh Thermal neutrality yay! Thermal delight

71 Rich, variable, multi-sensory environments

72 Experiential Monotony

73

74 Source:

75 Benefits of Biophilic Design Psychological & physiological stress reduction Lowered blood pressure and heart rate Improved mental engagement / attentiveness Reduced attentional fatigue Increased physical / mental health Shift to positive emotional states Mental restoration, cognitive function Improved rates of healing Entrainment of circadian rhythms NO evidence of negative effects

76 Occupant wellbeing How can we reward GOOD buildings? Winners: CBE Living Building Award

77 CBE Livable Buildings Awards design + occupant experience + energy performanc Awarded for exceptional performance in terms of occupant satisfaction, resource efficiency, and overall design Qualifying criteria Scores for all survey categories above 50 th percentile Overall building score above 75 th percentile Selection Submission of design, operation, and survey Jury review

78 Papers and publications Clif Bar Headquarters, Emeryville, CA. Zero Net Energy retrofit & winner of Living Building Award